Medulloblastoma symptoms may appear similar to those of other diseases, but you need to visit your doctor immediately after noticing them!

Medulloblastoma is a tumor that has historically been associated with the cerebellum, but it can also appear in other sections of intracranial tissue. Despite its apparent severity, the prognosis is usually good.

Medulloblastoma (MB) is a neuroectodermal tumor of the cerebellum that constitutes about 20% of brain tumors in children. It is a childhood malignant disease, since in adults it only accounts for 1% of intracranial tumor masses. A prevalence of 1 in every 909,000 childhood inhabitants in Europe is estimated.

Its histological variability is very high. Therefore, the survival rate of the child 5 years after diagnosis is variable, although it is estimated at an average figure of 70%. Learn more about it to be able to treat it on time!

What is a medulloblastoma?

Granule cells are the smallest cell bodies found in the brain. They are located within the granular layer of the cerebellum and are part of the nerve networks, participating in processes such as the development of memory and the reception of stimuli.

Until recently, medulloblastoma (MB) was believed to be a type of primitive supratentorial neuroectodermal tumor (PNET), but today it has been separated from this category, as it does not share enough characteristics with this type of neoplasm. Many MBs develop in the embryonic layer that will give rise to granule cells.

According to Statpearls, there are 4 variants of medulloblastoma and their prognosis varies. We tell you its peculiarities in the following lines.

  1. Medulloblastoma with WNT activation

It is the rarest subgroup of medulloblastoma and only corresponds to 10% of childhood MBs, as indicated by the Journal of Korean Neurosurgical Society. WNT medulloblastomas can arise from progenitor cells of the dorsal brainstem in the lower rhombic lip. Some of its characteristics are the following:

The gender ratio is 1: 1, or what is the same, affects men and women equally.

Its prognosis is very good, since the metastasis rate at the time of diagnosis is less than 10%. The pattern of recurrence once treated is very low.

It has been associated with alterations in the CTNNB1, TP53, DDX3X and SMARCA4 genes. In addition, it is associated with the monosomy of chromosome 6. This means that in each cell of the infant’s body there is only one copy of this chromosome, compared to the 2 expected copies (diploidy).

  1. Medulloblastoma with activation of SSH

SSH-type medulloblastomas present a bimodal distribution, manifesting with a peak incidence in early childhood and another in adolescence. They represent 30% of all medulloblastomas and, unlike the previous case, they usually appear in the hemispheres of the cerebellum.

This is one of the most common types of MB and arises from the mutation in the genes of the precursors that will give rise to the granule cells described above. Some of its characteristics are the following:

The gender ratio is 1: 1, as in the previous case.

The prognosis in infants is very good, but not so good in adolescents. The rate of metastasis at the time of diagnosis can increase up to 20% of all patients.

It is associated with mutations in the genes PTCH1, SMO, SUFU and others.

  1. Third group of medulloblastomas

They represent 25% of medulloblastomas and affect newborns and young children almost exclusively. On this occasion, the neoplasm occurs in the fourth cerebral ventricle and the percentage of metastasis at the time of diagnosis is almost 50%. It is more common in men than women (2: 1) and the overall prognosis is poor.

  1. Fourth group of medulloblastomas

This is the only type of medulloblastoma that happens in all age groups, including adults. Due to its wide range, it is the most common variant, representing 35% of the tables.

Up to 40% of patients with this type of medulloblastoma present with metastases at the time of diagnosis and a high percentage of them are men (3: 1). The prognosis of this tumor is intermediate in severity; better than in the previous case.

Possible causes of a medulloblastoma

Talking about causes in congenital cancer processes is a very difficult task, since only 10 to 15% of malignant neoplasms present some type of hereditary character.

Cancer is nothing more than a mutation in the genome of a cell line. When a cell undergoes certain genetic mutations (such as those we have mentioned in previous sections), it can stop responding to the rhythms of death and proliferation. Thus, the mutated line expands uncontrollably and gives rise to a tumor.

If this tumor is malignant, it will have unlimited growth and the mutated cells will be able to enter the bloodstream, in a clinical event known as metastasis. Medulloblastoma follows this same general premise.

Risk factors

Although we do not know fully the causes of medulloblastoma, there are some syndromes in connection to it, as the American Brain Tumor Association indicates. These are the most common:

  • Gorlin syndrome: a genodermatosis characterized by the early onset of multiple basal cell carcinomas. It is a pathology of an autosomal dominant nature.
  • Fanconi anemia: a congenital disease that affects the production of all types of blood cells in the bone marrow.
  • Turcot syndrome: an inherited disease characterized by the presence of colorectal adenomas or carcinomas and primary neoplasms of the central nervous system (CNS).
  • Li-Fraumeni syndrome: inherited pathology that notably predisposes to the appearance of many types of cancer.

Risk factors for developing medulloblastoma are completely beyond the control of the patient. They are all inherited syndromes and therefore a child can only be prevented from being born with them with proper family planning if the parents are carriers of the pathological genes.

Medulloblastoma symptoms

The journal Radiology shows us in a detailed and exact way the clinical medulloblastoma symptoms. Primary medulloblastoma symptoms usually arise in response to increased intracranial pressure in the patient, due to secondary hydrocephalus developed by tumor-causing obstructions.

Some of them are the following:

  • Severe headaches: They are the first symptom in young children. This sharp, stabbing headache is usually worse when the patient bends over and improves slightly after vomiting.
  • Nausea and vomiting.
  • Visual disturbances: like seeing double (diplopia).
  • Ataxia: difficulty moving, unsteady gait and clumsiness when performing coordinated movements.

If cancer cells metastasize, symptoms can spread to other parts of the body. The most common sites of metastasis are bone (78%), lymph nodes (33%), liver (15%), and lungs (11%). The survival rate in these cases is practically nil.

Diagnosis

Due to the rapid onset and aggressiveness of the symptoms (about 3 months), the diagnosis is quite simple. As soon as the professional suspects a maladjustment in the central nervous system, they indicate a series of tests to the patient. As the MSD Manual indicates, MRI is the way to go in almost all cases.

In this test, doctors use nuclear magnetic resonance phenomena to obtain information about the organ of interest; in this case, the brain. It is easy to detect any abnormality with this technique, but to ascertain what type of tumor affects the patient it is necessary to collect a sample of the tissue and analyze it (biopsy).

Possible treatments and prognosis

Each medulloblastoma has a different associated risk. Therefore, the treatment will vary in each patient and case, depending on their age, tumor location and degree of metastasis.

The standard treatment today is surgical removal, and then chemotherapy and radiation to kill neoplastic cell remnants. According to the stratification criteria for cancer patients, in this case up to 3/4 of those affected achieve a total cure.

In any case, up to 80% of patients have endocrine sequelae due to the tumor and the procedures, such as delays in cognitive dysfunctions or growth hormone deficiency. Scientists are developing new drugs that try to solve the effects of similar genetic mutations.

Early diagnosis for survival

Medulloblastoma is a type of cancer with a very heterogeneous clinical entity. Each variant has its peculiarities and, therefore, the urgency of the condition and the chances of metastasis are different each time. In any case, it should be noted that the survival rate is 70%.

Group 4 medulloblastoma (the most common of all) has an intermediate prognosis. Its probability of metastasis is almost 40%, while other variants are less aggressive. Survival depends on the time of detection, because the earlier the doctor diagnoses the cancer, the more likely it has not had time to spread. So, beware of any medulloblastoma symptoms and should you notice them, immediately visit your doctor!

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